1. Technical Field
This disclosure relates generally to communications devices and more particularly to signal conversion circuitry in a communication device.
2. Description of Related Art
Communication systems are well known and include wireless networks, wired networks, and various other types of networks. Wired networks use wiring or fiber to direct communications between communication devices while wireless networks support communications wirelessly. Examples of wired networks are optical networks, the telephone network, Local Area Networks (LANs), Wide Area Networks (WANs), and cable networks, etc. Examples of wireless networks include satellite networks, cellular networks, microwave networks, Wireless Local Area Networks (WLANs), Wireless Personal Area Networks (WPANs), and point to point Radio Frequency networks, etc.
As communications technology has advanced, integrated circuits have been developed that service both wired and wireless communications. Most communication devices, such as cellular telephones, digital modems, set top boxes, lap top computers, tablet computers, desk top computers, printers, and other communication devices include multiple integrated circuits. Integrated circuits that service communications typically include multiple Analog to Digital Converters (ADCs) and multiple Digital to Analog Converters (DACs). ADCs convert signals from analog format to digital format and DACs convert signals from digital format to analog format.
ADCs often must sample signals having voltage magnitudes and information signal bandwidths that vary over time. In order to compensate for these differing signals, ADCs operate at differing sampling frequencies and at differing sampling voltage ranges to satisfy their varying operational requirements. Supply voltages used to power integrated circuits that include the ADCs are typically constant over time. Thus, prior devices used linear regulator to provide the ADCs with voltages that differed from the supply voltage to enable wider sampling ranges. Using linear regulators to generate the ADC voltages increased ADC power consumption. Further, some desirable voltage levels could not be generated by the linear regulators, e.g., ADC voltages above the supply voltage and ADC grounds below the supply ground.
Other prior devices used switching regulators to generate the ADC voltages. However, using switching regulators increased I/O pin count, increased cost due to increased part count, and introduced power supply spurs that degrade performance. Further, external regulators were not optimized for required ADC characteristics such as sampling frequency, sampling bandwidth, and sampling signal range.